JP4068691B2 - Circuit board holding structure in infrared detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention holds a circuit board in a case such as a pyroelectric infrared detector, a thermopile infrared detector, a photodiode, or a phototransistor with a predetermined distance from the stem by at least three lead pins. The present invention relates to a circuit board holding structure in an infrared detector configured as described above.
[0002]
[Prior art]
For example, in a pyroelectric infrared detector, the infrared rays that have passed through the infrared transmission window formed in the case from the outside of the case are reliably collected on the light receiving portion of the pyroelectric element in the case. Therefore, it is necessary to hold the circuit board for holding the pyroelectric element on the upper surface at a predetermined position from the upper surface of the stem.
[0003]
Therefore, conventionally, as shown in, for example, Japanese Patent Application Laid-Open No. 64-47922 and Japanese Utility Model Laid-Open No. 4-107863, the circuit board is placed at a predetermined height position from the upper surface of the stem base by the lead pins. Hold on.
[0004]
FIG. 5 shows a pyroelectric infrared detector disclosed in Japanese Utility Model Laid-Open No. 4-107863. In FIG. 5, 51 is a metal case having an open bottom, and an infrared ray is formed on the upper surface thereof. A transmission window 52 is formed. A stem 53 closes the lower opening of the case 51. In the case 51, a circuit board 55 is provided at a predetermined interval with respect to the upper surface of the base 56 of the stem 53 by a plurality of lead pins 54 penetrating the stem 53.
[0005]
That is, a protrusion 57 is formed in the vicinity of the upper end of the lead pin 54, the upper end of the lead pin 54 is inserted through a through hole 58 provided in the circuit board 55, and the protrusion 57 is on the lower surface side of the circuit board 55. The circuit board 55 is held in a predetermined state. Reference numeral 59 denotes a conductive bonding material for bonding the upper end portion 60 of the lead pin 54 protruding to the upper surface side of the circuit board 55 and a conductor pattern (not shown) of the circuit board 55.
[0006]
A pyroelectric element 62 is provided on the upper surface of the circuit board 55 via an appropriate support material 61, and an FET 63 and a resistor 64 are provided on the lower surface side of the circuit board 55.
[0007]
In the conventional pyroelectric infrared detector, a protrusion 57 is formed on the upper end side of the lead pin 54, and the circuit board 55 is held by the protrusion 57 with a predetermined distance from the stem base 56. Therefore, circuit components such as the FET 63 and the resistor 64 can be mounted on the lower surface side of the circuit board 55.
[0008]
[Problems to be solved by the invention]
However, the pyroelectric infrared detector has the following problems. That is, the lead pin 54 has a stepped structure having a protrusion 57 having a special shape on the upper end side. However, since the lead pin 54 is provided with the protrusion 57 by processing the core wire, the number of processing steps increases. This increases the processing cost. And since the protrusion part 57 is located in the lower surface side of the circuit board 55, the effective area for component mounting on the lower surface side of the circuit board 55 decreases, arrangement | positioning of circuit components, such as FET63 and the resistor 64, and a circuit There is a problem that the configuration of the conductor pattern formed on the upper and lower surfaces of the substrate 55 is restricted. This restriction becomes more severe as the number of lead pins 54 increases. Further, when the lead pin 54 is bent, the insertion error increases when the lead pin 54 is inserted into the through hole 58 of the circuit board 55, or the lead pin 54 is broken, resulting in lower productivity. It was.
[0009]
Such a problem occurs not only in the pyroelectric infrared detector but also in a thermopile infrared detector, and also in a photodiode or a phototransistor. In other words, this occurs in an infrared detector configured to hold a circuit board in a case with a predetermined distance from the stem by at least three lead pins.
[0010]
The present invention has been made in consideration of the above-mentioned matters, and its purpose is to provide a circuit board in an infrared detector that can be easily assembled and has a high degree of freedom in mounting circuit components on both upper and lower surfaces of the circuit board. It is to provide a holding structure.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a circuit board having an infrared detection element on its upper surface is held in a case with at least a predetermined distance from the stem by at least three lead pins. In the configured infrared detector, the lead pin is formed in a straight shape having no protrusion, and the upper end of the straight lead pin is brought into direct contact with the lower surface of the circuit board, and the lower surface side of the circuit board The solder pattern is formed by connecting a conductor pattern formed by connecting to a circuit component mounted on the lead pin and the lead pin so as to surround the outer peripheral surface near the upper end of the lead pin and gradually increase in diameter toward the conductive pattern side. Electrically and mechanically coupled, the electrode formed on the infrared detection element on the upper surface side of the circuit board and the front surface on the lower surface side of the circuit board And a conductive pattern, that are connected excursion was through the conductive portion provided also led to the side walls of the through holes penetrating the circuit board portion of the portion electrically to the binding point of the upper end portion of the lead pin It is a feature.
[0012]
In the infrared detector of the present invention, the lead pin has a straight shape, and its upper end is brought into direct contact with the lower surface of the circuit board, and the conductor pattern formed on the lower surface of the circuit board and the lead pin are connected to the lead pin. Since the circuit board is held in such a manner as to be electrically and mechanically coupled by solder that surrounds the outer peripheral surface portion near the upper end portion and is gradually increased in diameter toward the conductive pattern side, There is no need to form special protrusions, so the lead pins can be manufactured in a simpler process, the effective mounting area on both the upper and lower sides of the circuit board is increased, circuit component placement and circuit board formation The configuration of the conductor pattern is not restricted.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. 1 to 4 show one embodiment of the present invention. 1 and 2, reference numeral 1 denotes a metal case having an opening at the bottom, an opening 2 having a predetermined shape formed on the upper surface, and an infrared ray made of an infrared transmitting material so as to seal the opening 2. A transmission window 3 is provided. 4 is a stem for closing the lower opening of the case 1, 5 is a base thereof, 6 is a flange formed on the outer periphery of the lower part of the base 5, and 7 is a protrusion protruding outward from a part of the outer periphery of the flange 6. is there.
[0014]
8 is a circuit board having, for example, a regular octagonal plan view provided in the case 1, and a pyroelectric element 10 is provided on the upper surface of the circuit board via a support member 9 also serving as an appropriate conductive portion. A circuit pattern such as an FET 11 and a resistor 12 is mounted and a conductor pattern 13 is formed. Reference numeral 14 denotes a conductive portion for electrically connecting the electrode 15 formed on the pyroelectric element 10 provided on the upper surface side of the circuit board 8 and the conductor pattern 13 on the lower surface side of the circuit board 8. As shown in the figure, the lead is also guided to the side wall of the through hole 16 that penetrates the portion of the circuit board 8 at a location displaced from the joint location of the upper end portion of the lead pin 17 described later .
[0015]
The configuration up to this point is not different from the conventional pyroelectric infrared detector. The present invention is greatly different from the conventional pyroelectric infrared detector in the holding structure of the circuit board 8.
[0016]
That is, in FIG. 1, reference numeral 17 denotes, for example, three lead pins inserted into the case 1 through the through hole 18 provided in the stem 4, all of which are formed so as to exhibit a straight shape, It is arranged to form. The lead pins 17 are provided so as to protrude from the stem base 5 by the same length so that the upper end portions 17a thereof are at the same height, and in this state, the through holes 18 are hermetically filled. It is fixed by an insulating material 19 such as glass provided.
[0017]
The circuit board 8 is held in a horizontal state so that the lower surface of the circuit board 8 is brought into contact with the upper end portion 17a of the lead pin 17 that is erected and fixed to the stem 4 as described above. The conductive pattern 13 formed on the lower surface 8a of the circuit board 8 thus held, the upper end portion 17a of the lead pin 17 and the vicinity thereof surround the outer peripheral surface portion in the vicinity of the upper end portion 17a of the lead pin 17, and the conductive pattern 13 They are electrically and mechanically connected by solder 20 that is formed in an approximately inverted triangle shape so that the diameter gradually increases toward the side.
[0018]
In the pyroelectric infrared detector having the above-described configuration, the lead pin 54 for holding the circuit board 55 has a protrusion 57 in the vicinity of its upper end, as in the conventional circuit board holding structure shown in FIG. While the formed stepped structure is provided, a hole 58 for inserting the lead pin 54 is provided in the circuit board 55, and the lead pin 54 is inserted into the hole 58 to hold the lower surface of the circuit board 55 in contact with the protrusion 57. Instead, the circuit board 8 is held so that the lower surface 8a thereof is simply brought into contact with the upper end portion 17a of the lead pin 17 projecting from the upper surface of the stem base 5. The structure of 8 is very simple.
[0019]
That is, it is not necessary to form a special protrusion on the lead pin 17 and it may be a simple shape. Therefore, the lead pin 17 can be manufactured by a simpler process, and the lead pin 17 is inserted into the hole on the circuit board 8 side. There is no need to insert it, and even if the lead pin 17 is bent to some extent, it will not be broken.
[0020]
In the circuit board 8, it is not necessary to provide a hole for inserting the lead pin 17, and the region where the lead pin 17 protrudes and the through hole 58 (see FIG. 5) is formed on the upper surface while being held by the lead pin 17. Therefore, the upper surface can be used widely, and there is no extra protrusion on the lower surface, so the effective mounting area increases even if the device is downsized, and the arrangement of components and the configuration of the conductor pattern formed on the circuit board are reduced. There are no restrictions and the degree of freedom of design increases.
[0021]
Combined with the above, the yield of the pyroelectric infrared detector is improved and the productivity is greatly improved, so that a high-quality pyroelectric infrared detector can be produced at low cost and in large quantities.
[0022]
3 and 4 show an example of a process of holding the circuit board 8 in a predetermined state with respect to the stem 4 having the three lead pins 17 (hereinafter referred to as the stem 4A with lead pins). That is, when the pyroelectric infrared detector S having the above-described configuration is manufactured, it may be manufactured one by one, but it is generally reasonable to manufacture a plurality of them at once.
[0023]
In FIG. 3, reference numeral 21 denotes a metal stem tray having an appropriate thickness, and a plurality of stem holding portions 23 each having three through holes 22 at the vertices of a right-angled isosceles triangle (9 in this example). Is formed. By doing in this way, nine stems 4A with a lead pin can be held in a predetermined state.
[0024]
Reference numeral 24 denotes a circuit board assembly in which a plurality of (9 in this example) circuit boards 8 are formed so as to correspond to the stems 4A with lead pins held by the stem holding part 23. The stem 4A is set on the stem tray 21 so as to come into contact with the upper end portion 17a of the lead pin 17 from the upper part of the stem 4A with the lead pin set at the position.
[0025]
In this case, in order to make the conductor pattern 13 on the lower surface side of each circuit board 8 correspond to the upper end portion 17a of the lead pin 17 of each stem 4A with lead pins, the following members are attached to the stem tray 21 and the circuit board assembly 24. Is provided. That is, the guide pins 25a and 25b are erected at appropriate two locations on the stem tray 21, while the circuit board assembly 24 is penetrated by the guide pins 25a and 25b at positions corresponding to the guide pins 25a and 25b. Holes 26a and 26b are provided.
[0026]
By doing so, the upper end portion 17a of each lead pin 17 in the nine stems 4A with lead pins held by the stem tray 21 and the lower surface side of the nine circuit boards 8 provided in the circuit board assembly 24 are arranged. The circuit board assembly 24 can be set on the stem tray 21 in a state in which the formed conductor patterns 13 are correctly associated with each other without being misaligned (see FIG. 4).
[0027]
In the above-described embodiment, the circuit board 8 is held by the three lead pins 17. However, the present invention is not limited to this, and the number of the lead pins 17 may be four or more. Needless to say.
[0028]
The present invention can be applied not only to the pyroelectric infrared detector S but also to a thermopile infrared detector, a photodiode or a phototransistor.
[0029]
【The invention's effect】
According to the present invention, the degree of freedom of mounting components on both the upper and lower surfaces of the circuit board held by the lead pins is greatly increased, and even when the number of lead pins is increased, the connection with the board is easy and the productivity is increased. Therefore, it is possible to produce a large amount of optical elements that are small and have excellent performance at a low cost.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a pyroelectric infrared detector as an example of the present invention.
FIG. 2 is an exploded perspective view of the pyroelectric infrared detector.
FIG. 3 is an exploded perspective view for explaining a part of the manufacturing process of the pyroelectric infrared detector.
FIG. 4 is a longitudinal sectional view of an essential part for explaining the manufacturing process.
FIG. 5 is a longitudinal sectional view showing a conventional pyroelectric infrared detector.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Case, 4 ... Stem, 4A ... Stem with lead pin, 8 ... Circuit board, 8a ... Lower surface of a circuit board, 13 ... Conductor pattern, 14 ... Conductive part, 15 ... Electrode, 16 ... Through hole, 17 ... Lead pin, 17a ... upper end of lead pin, 20 ... solder.

Claims (1)

In the infrared detector configured to hold a circuit board having an infrared detection element on its upper surface in a case with a predetermined distance from the stem by at least three lead pins, the lead pin is a protrusion. It is formed in a straight shape that does not have a portion, and the upper end portion of this straight-shaped lead pin is directly brought into contact with the lower surface of the circuit board and is connected to a circuit component mounted on the lower surface side of the circuit board. The circuit pattern and the lead pin are electrically and mechanically coupled by solder that surrounds the outer peripheral surface near the upper end of the lead pin and is gradually increased in diameter toward the conductive pattern side, and the conductive pattern on the lower surface side of the electrode and the circuit board forming the infrared detection element having a top side of the substrate, on the lead pin Circuit board in the infrared detector, characterized in that connected excursion to a circuit board portion of the portion through the conductive portion provided also led to the side walls of the through holes penetrating electrically the binding portion of the part Holding structure.

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